Mechanical modelling of the source of glacial earthquakes in polar regions
Estimating the mass balance of the polar ice caps is a current challenge to understand the rapid evolution of these ice masses under the effect of climate change. The calving of icebergs represents a significant part of the mass loss of Greenland's glaciers. Their capsize near the terminus dest...
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2021
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Online Access: | https://theses.hal.science/tel-04046993 https://theses.hal.science/tel-04046993/document https://theses.hal.science/tel-04046993/file/BONNET_Pauline_va.pdf |
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ftunivparis:oai:HAL:tel-04046993v1 2023-06-11T04:11:55+02:00 Mechanical modelling of the source of glacial earthquakes in polar regions Modélisation mécanique de la source des séismes glaciaires en régions polaires Bonnet, Pauline Institut de Physique du Globe de Paris (IPGP (UMR_7154)) Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) Université Paris Cité Anne Mangeney Olivier Castelnau 2021-06-07 https://theses.hal.science/tel-04046993 https://theses.hal.science/tel-04046993/document https://theses.hal.science/tel-04046993/file/BONNET_Pauline_va.pdf en eng HAL CCSD NNT: 2021UNIP7265 tel-04046993 https://theses.hal.science/tel-04046993 https://theses.hal.science/tel-04046993/document https://theses.hal.science/tel-04046993/file/BONNET_Pauline_va.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-04046993 Earth Sciences. Université Paris Cité, 2021. English. ⟨NNT : 2021UNIP7265⟩ Glaciers Iceberg Capsize Mechanical modelling Greenland Icequakes Retournement Modélisation mécanique Groenland [SDU.STU]Sciences of the Universe [physics]/Earth Sciences [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology info:eu-repo/semantics/doctoralThesis Theses 2021 ftunivparis 2023-05-03T16:18:18Z Estimating the mass balance of the polar ice caps is a current challenge to understand the rapid evolution of these ice masses under the effect of climate change. The calving of icebergs represents a significant part of the mass loss of Greenland's glaciers. Their capsize near the terminus destabilises the glaciers. Using a reference fluid dynamics model, we quantified and characterised the interaction between water and a capsizing iceberg, and validated and improved a simplified iceberg capsize model. Then we built and validated a finite element model that reproduces the response of a glacier to the contact force of a capsizing iceberg at the terminus and that includes several rheologies of the glacier/rock interface and a visco-elastic behaviour of the ice. Using this comprehensive model, we reproduced surface displacements and stresses at the base of the glacier and analysed the influence of the parameters on the glacier response. We first modelled a glacier with an idealised geometry. Then we modelled a real glacier, the Helheim glacier, and for this we adjusted the model parameters using results from a reference glacier flow model. A strong dependence of the amplitude of the surface displacements on the Young's modulus of the ice and the length of the floating tongue is observed, but also a signature of the viscosity and the friction law parameters on these displacements. The results obtained with the full model open interesting perspectives on the estimation of the parameters of the rheology, geometry and basal friction laws through comparison with field observations. L’estimation du bilan de masse des calottes polaires est un enjeu actuel pour appréhender l’évolution rapide de ces masses glaciaires sous l’effet du changement climatique. Le vêlage d’icebergs représente une part importante de la perte de masse des glaciers du Groenland. Leur retournement proche du terminus déstabilise les glaciers. A l'aide d'un modèle de référence de dynamique des fluides, nous avons quantifié et caractérisé ... Doctoral or Postdoctoral Thesis glacier Greenland Groenland Université de Paris: Portail HAL Greenland Vêlage ENVELOPE(140.023,140.023,-66.671,-66.671) |
institution |
Open Polar |
collection |
Université de Paris: Portail HAL |
op_collection_id |
ftunivparis |
language |
English |
topic |
Glaciers Iceberg Capsize Mechanical modelling Greenland Icequakes Retournement Modélisation mécanique Groenland [SDU.STU]Sciences of the Universe [physics]/Earth Sciences [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
spellingShingle |
Glaciers Iceberg Capsize Mechanical modelling Greenland Icequakes Retournement Modélisation mécanique Groenland [SDU.STU]Sciences of the Universe [physics]/Earth Sciences [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology Bonnet, Pauline Mechanical modelling of the source of glacial earthquakes in polar regions |
topic_facet |
Glaciers Iceberg Capsize Mechanical modelling Greenland Icequakes Retournement Modélisation mécanique Groenland [SDU.STU]Sciences of the Universe [physics]/Earth Sciences [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology |
description |
Estimating the mass balance of the polar ice caps is a current challenge to understand the rapid evolution of these ice masses under the effect of climate change. The calving of icebergs represents a significant part of the mass loss of Greenland's glaciers. Their capsize near the terminus destabilises the glaciers. Using a reference fluid dynamics model, we quantified and characterised the interaction between water and a capsizing iceberg, and validated and improved a simplified iceberg capsize model. Then we built and validated a finite element model that reproduces the response of a glacier to the contact force of a capsizing iceberg at the terminus and that includes several rheologies of the glacier/rock interface and a visco-elastic behaviour of the ice. Using this comprehensive model, we reproduced surface displacements and stresses at the base of the glacier and analysed the influence of the parameters on the glacier response. We first modelled a glacier with an idealised geometry. Then we modelled a real glacier, the Helheim glacier, and for this we adjusted the model parameters using results from a reference glacier flow model. A strong dependence of the amplitude of the surface displacements on the Young's modulus of the ice and the length of the floating tongue is observed, but also a signature of the viscosity and the friction law parameters on these displacements. The results obtained with the full model open interesting perspectives on the estimation of the parameters of the rheology, geometry and basal friction laws through comparison with field observations. L’estimation du bilan de masse des calottes polaires est un enjeu actuel pour appréhender l’évolution rapide de ces masses glaciaires sous l’effet du changement climatique. Le vêlage d’icebergs représente une part importante de la perte de masse des glaciers du Groenland. Leur retournement proche du terminus déstabilise les glaciers. A l'aide d'un modèle de référence de dynamique des fluides, nous avons quantifié et caractérisé ... |
author2 |
Institut de Physique du Globe de Paris (IPGP (UMR_7154)) Institut national des sciences de l'Univers (INSU - CNRS)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité) Université Paris Cité Anne Mangeney Olivier Castelnau |
format |
Doctoral or Postdoctoral Thesis |
author |
Bonnet, Pauline |
author_facet |
Bonnet, Pauline |
author_sort |
Bonnet, Pauline |
title |
Mechanical modelling of the source of glacial earthquakes in polar regions |
title_short |
Mechanical modelling of the source of glacial earthquakes in polar regions |
title_full |
Mechanical modelling of the source of glacial earthquakes in polar regions |
title_fullStr |
Mechanical modelling of the source of glacial earthquakes in polar regions |
title_full_unstemmed |
Mechanical modelling of the source of glacial earthquakes in polar regions |
title_sort |
mechanical modelling of the source of glacial earthquakes in polar regions |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://theses.hal.science/tel-04046993 https://theses.hal.science/tel-04046993/document https://theses.hal.science/tel-04046993/file/BONNET_Pauline_va.pdf |
long_lat |
ENVELOPE(140.023,140.023,-66.671,-66.671) |
geographic |
Greenland Vêlage |
geographic_facet |
Greenland Vêlage |
genre |
glacier Greenland Groenland |
genre_facet |
glacier Greenland Groenland |
op_source |
https://theses.hal.science/tel-04046993 Earth Sciences. Université Paris Cité, 2021. English. ⟨NNT : 2021UNIP7265⟩ |
op_relation |
NNT: 2021UNIP7265 tel-04046993 https://theses.hal.science/tel-04046993 https://theses.hal.science/tel-04046993/document https://theses.hal.science/tel-04046993/file/BONNET_Pauline_va.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1768387357481893888 |